JPH0398444A - Variable speed induction motor - Google Patents

Abstract

PURPOSE:To permit the employment of the title motor for an apparatus having any load characteristic by a method wherein one stator coil is short-circuited while the other stator coil is provided with the rotary magnetic field of reverse phase upon braking. CONSTITUTION:When signals are outputted from a signal outputting means, not shown in a diagram, into relays 52, 53, 55 in the connection of normal rotation, which is shown in the diagram, to flick switches M4, M5, the phase of one of stator coils becomes the opposite one by the switch M4 while the connection of a motor becomes Y-connection by the switch M5. On the other hand, the power supplying terminals of the other stator coil are short-circuited in the condition of -connection as it is by the switching of switches M6, M7 and, therefore, an electromotive force is generated by the rotation of a rotor 7. The electromotive force, thus generated, is consumed by the conductor resistance of the short-circuited stator coil and the like. In this case, a braking torque is changed variously by the pivoting of a pivoting stator. One stator coil is short-circuited and the power source of reverse phase is supplied to the other stator coil in such a manner that a variable speed induction motor, capable of coping with all kinds of load torques, is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention has a single rotor and a plurality of stators, and by rotating an arbitrary stator, the rotor can be rotated to face the stator. The present invention relates to a braking device for acceleration control of a variable speed induction motor that can arbitrarily change the rotational speed and generated torque of the rotor by creating a phase difference in the voltage induced in the rotor conductor portion.

[Conventional technology]

For example, conventional techniques for controlling the operating speed of electric cargo handling machines include inverters, pole number switching, voltage control, etc. for electrical purposes, and transmission devices for mechanical purposes. In addition, efforts have been made to use these devices and methods in combination to reduce vibrations and shocks caused by changes in the speed of transport or movement of loads being transported, moved, or lifted.

Although the speed of constant-speed running and movement can be controlled using the above-mentioned conventional technology, it is difficult to control the acceleration in the acceleration range up to constant-speed running or from constant-speed running to stopping. In order to control the speed until it reaches a desired speed within a certain period of time, expensive equipment is required.

[Problem to be solved by the invention]

Such acceleration control includes positive and negative acceleration, and of both, negative acceleration is called braking, and many electrical methods are available. For example, reverse phase braking, DC braking, dynamic braking,
This includes unbalanced braking.

Regarding anti-phase braking, there is Japanese Patent Publication No. 63-34709, which uses an inverter to lower both the frequency and voltage than the maximum value during operation in the first phase order, and a second phase brake that is opposite to the first phase order. This applies phase-sequential output to a three-phase AC motor to perform anti-phase braking. These require an inverter device to match the electric motor.

In addition, both dynamic braking and unbalanced braking require expensive braking control circuits, and each method, including reverse-phase braking,
It is necessary to use it properly depending on the size and frequency of D2. For example, in addition to the above-mentioned anti-phase braking, DC braking has been used for braking hoisting machines since ancient times, capacitor braking is mainly used for braking at relatively high speeds such as on ropeways, and single-phase braking is suitable for soft braking because its braking torque is relatively small. This is known from the prior art.

According to the above-mentioned prior art, each electrical braking method exhibits unique braking torque characteristics and its characteristic curve is uniquely determined, so the scope of use and equipment used are limited by each braking method. Furthermore, each braking device used an inverter and large-capacity elements (Sirisk), making it an expensive device.

In view of the above, our technical objective is to provide a variable speed induction motor and its braking device, which can be used in equipment with various load characteristics using the same braking device, has a simple structure, and can be manufactured at low cost. It is.

[Means to solve the problem]

The present invention provides a rotor in which a plurality of conductors attached to a plurality of rotor cores provided at arbitrary intervals on the same rotating shaft are connected in a continuous manner, and a rotor facing each of the rotor cores. a plurality of stators in which windings are connected in parallel and are fixedly installed, and at least one of the plurality of stators is rotated concentrically with the rotor. In the variable speed induction motor formed in the stator, the plurality of stators are provided with a reverse phase device that switches the direction of the rotating magnetic field of the stator in the opposite direction, and further, the reverse phase device is provided with a Y-△ switching together with the reverse phase device. The above problem is solved by providing the device and by providing voltage regulators for a plurality of stators.

Further, according to the present invention, in the variable speed induction motor, a switching device is provided on one stator winding for connecting to a power source during operation and shorting the winding terminals during braking, and a switching device is provided on the other stator winding for connecting to a power source during operation and short-circuiting the winding terminals during braking. The above-mentioned problem was solved by providing a reverse-phase device that is connected to the reverse phase during braking and connected to the reverse phase during braking.

[For production]

The variable speed induction motor of the present invention changes the rotation speed of the rotor and the generated torque by creating a phase difference in the rotating magnetic field between the stators by rotating the rotating stator. This makes it possible. When braking this variable speed induction motor using a reverse phase device, if a phase difference is provided, the braking torque changes in accordance with the phase difference, making it possible to generate various braking torque characteristics. In addition to operating the stator with a delta connection to the power supply and then switching to reverse-phase braking, it is also possible to change the braking force to the Y-connection and then switch to reverse-phase braking due to the difference in line voltage between the Y-connections. It is possible to achieve a softer braking force that is lower than that when the Δ connection is made. Furthermore,
The braking force can be controlled by the phase difference caused by rotation, but for example, when a braking force lower than the braking force within the phase difference range (0° to 180° electrical angle) is required, the supply voltage of the stator is lowered. By doing so, the braking force can be kept low.

Also, when braking, if one stator winding is short-circuited and a rotating magnetic field of opposite phase is applied to the other stator winding, the other stator will brake the rotor in reverse phase, and due to this magnetic field of opposite phase. The current induced in the rotor conductor causes an induced current to flow through one of the short-circuited stator windings, and is configured to perform anti-phase braking on one side and dynamic braking on the other.

In this case as well, the braking torque can be varied in various ways by rotating the rotating stator. Furthermore, the braking torque can also be changed by providing a variable resistance at the short-circuit point of one stator winding.

From the above, the rotation of the rotating stator, the reverse phase device, and the Y
- Any load torque or It has become possible to provide a variable speed induction motor in the simplest manner and at a low cost, which is capable of responding to the above-mentioned changes in GD2 at the same load.

Furthermore, the rotation of the stator by the stator rotation means is effective in both speed increase and braking, and it is possible to obtain various torque characteristic curves and braking torque curves by rotation.

〔Example〕

Although the invention will mainly be described in detail with reference to a two-stator induction motor with a squirrel-cage rotor, it goes without saying that the invention is not limited thereto. In addition, as mentioned above, there are cases where there are multiple induction motors with wound rotors, and there are cases where the stator windings are switched between star connection and delta connection to further diversify the torque characteristics. . The structure between the rotor cores may also use spaces, non-magnetic materials, magnetic materials, etc.

The present applicant has already given a detailed explanation of the structure and operation of an induction motor consisting of a plurality of stators, which is a part of the structure of the present invention, in Japanese Patent Application No. 128314/1982. This will be explained based on FIGS. 1 to 5.

An embodiment of an electric motor forming a part of the structure of the present invention will be explained with reference to FIG. Reference numeral 1 denotes a variable speed induction motor according to the present invention, and the induction motor 1 has the following configuration.

Rotor cores 2 and 3 made of magnetic material are mounted on a rotor shaft 4 with an arbitrary interval provided therebetween. A non-magnetic core 5 is interposed between the rotor cores 2 and 3, or a space is provided between the rotor cores 2 and 3. Each of the plurality of conductors 6 installed in the rotor core 2.3 is connected in communication with the rotor core 2, 3 to form an integral rotor 7, and a plurality of conductors 6 connected in series are connected to each other to form an integral rotor 7. Both ends of the conductors 6 are short-circuited by a short-circuit ring 8.8. In addition, in this embodiment, the conductors 6 installed in the rotor 7 are energized when a current with an arbitrary vector difference flows through each of the non-magnetic core 5 portions between the rotor cores 2 and 3. They are connected via a resistive material 9.

A first stator 12 and a second stator 13 having windings 1o and 11 on their outer sides facing the rotating cores 2 and 3 are arranged side by side on a machine frame 14, and the machine frame 14 and the first stator 12 are A sliding bearing 15 is installed, and the second stator 13 is fixed to the machine frame 14. Here, the stator rotation device will be explained. A gear 17 is fitted to one side surface of the first stator 12. A driving gear 21 is pivotally attached to a rotating electric motor 20 fixed to the outer periphery of the machine frame 14, and the driving gear 21 is engaged with a gear 17 fitted to the first stator 12.

With this configuration, the first stator 12 forms a rotary stator 16 that rotates concentrically with the four rotors 7 by the operation of the rotary electric motor 20. Thus, the rotation of the first stator 12 and the second stator 13 constitute a voltage phase shifting device.

A speed detector 22 is associated with the rotor shaft 4 of the rotor 7 . In this case, either a non-contact type or a contact type may be used.

In addition, the windings 10.1 of the l-th stator 12 and the second stator 13
The first form may be either a Δ connection or a Y connection. In the following first embodiment, operation is performed with the Δ connection, and braking is performed with the Y connection.

Next, a first embodiment of the present invention is shown in FIG.

The power source 30 has a power switch device 31, a reverse phase device 43, and Y1△
The induction motor 1 is connected via a switching device 44 .

Further, the power supply 30 is connected to a control device 34 consisting of a control section 32 and an operation process storage section 33, and the control section 32 has the power switching device 31, a reverse phase device 43, a Y-Δ switching device 44, and a speed control device 34. The detector 22 and the stator rotation device 35 are connected.

Furthermore, the control section 32 will be explained. The block diagram is shown in Fig. 3. According to the block diagram, the signal input means 40 inputs the signal of the speed detector 22 every minute time, the calculation means 37 performs calculation processing on the speed signal of the input means 40, and the operation is performed via the result of the calculation means 37 and the control means 41. Comparing means 38 for comparing the operating process data sent from the process storage section 33; signal output means 39 for outputting a positive or negative rotation signal to the rotating device 35 according to the result of the comparing means 38; and a signal outputting means 39 for controlling these. It is constituted by a control means 41. By the way, it is assumed that the control means 41 has a microcomputer configuration using a microprocessor, which is implemented by current technical means.

The power switching device fl31, the reverse phase device 43, and the Y-Δ switching device 44 are controlled by the control device 41 via the signal output device 39. Further, the signal input means 40 may be manually inputted with an external input signal 42 from an external position sensor, for example, a stop position sensor of an automated warehouse.

Next, FIG. 4 shows the operating process stored in the operating process storage section 33. In this operation process, an arbitrary rated speed is set as V1, and the time from starting to the rated speed is set as T1. This gives acceleration. v2 is the low speed just before reaching the arbitrary stop position, and T2 is the time to decelerate from the speed V1 to ■2. Incidentally, the timing of deceleration is determined by an external position sensor or an external signal from an operator's operation, and the same applies to stopping.

FIG. 5 is an example of the torque characteristic curve of the induction motor according to the present invention, and shows part of the change in the torque curve when the rotating stator is rotated from 0° to 180° (electrical angle). ing.

Next, the connections of the stator windings 10, 11 will be explained with reference to FIG. 6, and the changeover switches between the reverse phase device 43 and the Y-Δ switching device rIl 44 for switching the connections will be explained with reference to FIGS. 6 and 7.

What is shown in FIG. 6 is the connection of stator windings 10 and 11, which can be switched to both Y connection and Δ connection in parallel connection. M1 and M2 are switches, and the connection is switched between Y connection and Δ connection by alternately opening and closing the two interlocking switches. Further, the opening and closing of M3 is to switch the rotation direction of the rotating magnetic field of the two stators connected in parallel, and the alternate opening and closing of the two switches results in forward and reverse rotation. The state shown in Fig. 6 is a parallel △ connection, and the switches Ml, M2, and M3 are switched in the forward rotation direction (M11 closed, Mη=open, M21=closed, Mη=
open, M3,=closed, M,'2=open).

FIG. 7 shows a simple sequence circuit that operates to open and close switches M1, M2, and M3.

The reverse phase device 43 is provided with a coil 45 that operates the switch M3 and a relay 46 that operates with the output signal of the signal output means 39, and is constituted by the switch M3, the coil 45, and the relay 46.

Next, the Y-△ switching device 44 is provided with coils 47, 49 that operate the switches M1 and M2, and a relay 48 that operates with the output signal of the signal output means 39.
7. Consists of a coil 49 and a relay 48. In the state shown in FIG. 7, both relay 46 and relay 48 are OFF, and no voltage is applied to coil 45, coil 47, and coil 49.

Next, braking will be explained. If the rotation direction of the induction motor in the connection shown in Fig. 6 is forward rotation, M3 is switched (
M 3 1 = open, M32 = closed), it becomes a rotating magnetic field in the reverse direction of rotation, and serves as a brake against forward rotation.

Furthermore, when the switches M1 and M2 are switched at the same time as M3, each stator winding becomes Y-connected, which results in soft braking compared to the Δ-connection, allowing braking with less shock. If the rotary stator 16 is rotated when this braking action is generated, the braking torque will change according to each arbitrary rotation angle. The braking torque characteristics at this time are shown in FIG. The one in FIG. 8 shows the reverse phase braking torque in the Y connection of the present invention. As shown in Fig. 8, the braking torque at a given rotation angle varies by changing the rotation angle of the rotation stator 16 (the numbers in vi!J are electrical angles), and the It can also respond to fluctuations and changes in GD2.

Further, depending on whether the rotor is of a high resistance type or a low resistance type, this braking torque curve also changes to an upward trend or a downward trend to the right, and has various changes.

In this embodiment, as described above, braking is performed using a Y connection (braking torque shown in FIG. 8). However, the present invention is not limited to this embodiment, and various combinations of the low resistance type and the Δ connection can be realized depending on the application.

The effect of the above configuration will be explained. When a start signal is externally input to the control means 41 from the signal input means 40,
The control means 41 connects the power switchgear 3 via the signal output means 39.
Close 1. At this time, the rotation angle (electrical angle) of the motor is located on the side where the phase difference is large, for example, 1800 degrees.

The signal sent from the speed detector 22 is input to the signal input means 4.
It is input to the calculation means 37 via 0.

The arithmetic processing means 37 sends the speed change in the minute time Δt to the comparison means 38 as acceleration.

The comparison means 38 compares the acceleration value up to the rated speed given from the operation process storage section 33, and outputs a positive signal if the acceleration is small, and a 0 or negative signal if the acceleration is large, from the signal output means 39 to the stator. Output to the rotation device 35.

Furthermore, since the rotational speed at any given time is given by the operating process, both the acceleration and the rotational speed at that time are compared using the speed detector 22 and the value in the operating process storage section, and from the comparison between the two, A signal is output to the stator rotating means to stably accelerate the stator to the rated speed v1 during the time T1. In this way, the speed detector 22
Compare the speed value with the arbitrary value or predetermined acceleration stored in the operating process storage unit 33, and rotate the rotary stator using the stator rotation device based on the resulting difference, The torque characteristics are varied in various ways, and the torque characteristics are larger than the load torque to gradually shift to a high speed range, that is, the phase difference is gradually shifted to a high speed range in the direction of 180°→0°. In addition, for constant speed rotation, the rotating stator position is set by controlling the intersection of the load torque and the torque characteristic of the electric motor to a target rotation speed.

? For deceleration, when an external signal, etc. from a stop sensor or an operator's operation is input from the signal input means 40, the control means 4l sends a signal to the reverse phase device 43 and the Y△ switching device 44 via the signal output means 39. A signal is output to activate relays 46 and 48, and coils 45 and 47 are activated.
is applied to the coil 49. The switches M1, M2, and M3 are operated by the application to the coils 45, 47, and 49, and the Δ connection is switched to the Y connection, and the direction of the rotating magnetic field is reversed. (M11 Ichikai,
J2=closed, M21=open, M22=closed, M31=open, M3
■ = closed).

Since the rotating magnetic field is in the opposite direction, the induction motor 1 is used for braking.

At this time, the rotation angle (electrical angle) of the electric motor is located on the side where the phase difference is small, for example, O0. Furthermore, the braking torque is 8th
According to the figure, a braking torque with a phase difference (electrical angle) o0 is generated.

The signal sent from the speed detector 22 is input to the signal input means 4.
It is input to the calculation means 37 via 0.

The arithmetic processing means 37 sends the speed change in the minute time Δt to the comparison means 38 as a negative acceleration. Comparison means 38
compares it with the negative acceleration value up to the rated speed V2 given from the operating process storage section 33, and outputs a positive signal if the negative acceleration is small, and a 0 or negative signal if the acceleration is large. The output is then output to the stator rotation device 35. Furthermore, since the rotational speed at an arbitrary elapsed time is given by the operating process, both the negative acceleration and the rotational speed at that time are compared by the speed detector 22 and the value in the operating process storage unit, and both the negative acceleration and the rotational speed at that time are compared. Based on the comparison, a signal is output to the stator rotating means, and the stator is stably accelerated to the rated speed (2) during the T2 time. In this way, the speed value from the speed detector 22 is compared with the value at any time or the predetermined acceleration stored in the operating process storage section 33, and the rotating stator is rotated based on the difference. It is rotated by a drive device, and the torque characteristics are varied in various ways, and the braking torque characteristics of the Y-connection are used to gradually shift the speed to a low speed range.

When the speed reaches v2 by performing braking as described above, control is performed so that the intersection of the load torque and the torque characteristic of the electric motor becomes the target rotational speed v2. This control is to maintain the speed 2 by either controlling the braking torque to a small value depending on the inertial force of the load, or by switching the switch M2 to the forward rotation direction, although this varies depending on the inertial force of the load. Finally, when the stop position sensor or the operator's stop operation is input from the signal input means 40, the control means 41 controls the signal output means 3.
9 outputs a signal to the power supply opening/closing device 31 to open the power supply and to stop the power supply by an arbitrary mechanical braking device.

By the way, as mentioned above, in this embodiment, the two stator windings are connected in parallel to the power supply, and the connection is switched to △ connection during operation and Y connection during control, so that the two stators are rotated in the opposite direction. We have shown a system that performs braking by performing reverse phase switching to apply a magnetic field, but Y
It is also possible to perform anti-phase braking with the △ connection without performing the △ switching.

The braking torque is controlled by the rotation of the rotary stator, but when a braking torque smaller than the braking torque when the rotary stator is rotated at 180 degrees in electrical angle in Fig. 8 is required, this The invention uses a voltage regulator. Since the driving torque is proportional to the square of the voltage, it also affects the braking torque.
Even if the braking torque due to rotation of the rotating stator is out of the control range, the control range can be further expanded by adjusting the voltage.

Next, a second embodiment will be explained with reference to FIGS. 9 and 10. In this case, one stator performs dynamic braking and the other stator performs reverse phase braking, and either a fixed stator or a rotating stator may be used.

What is shown in FIG. 9 is a wiring diagram of the second embodiment, in which M4, M5, M6, and M7 are switches in parallel connection.

Switching to reverse phase is performed by opening and closing M4, and switching to reverse phase by opening and closing M.
- The switch of △ is switched between power supply to the △-connected winding and short circuit by opening and closing M6 and M7. In the state shown in Figure 9, are both stators connected in parallel to the three-phase power supply? It shows the status. (M a + = closed, M4 = open, M,
1=closed, M, 2=open, M6,=closed, M6■=open, M
7, = closed, M, 2 = open) The switches shown in Fig. 10 are M+, M2, M3.
, M4 is a simple sequence circuit.

Here, the reverse phase device 43 is a coil 5 that operates the switch M4.
0 and the output signal of the signal output means 39
are provided, switch M4, coil 50, and relay 52.
It is composed of.

Next, the Y-△ switching device 44 is provided with a coil 51 that operates the switch M, and a relay 53 that operates with the output signal of the signal output means 39, and is constituted by the switch M5, the coil 51, and the relay 53. Ru. Finally, reference numeral 60 is a switching device for dynamic braking, which is provided with coils 54 and 56 that operate the switches Mb and M7, respectively, and a relay 66 that operates with the output signal of the signal output means 39.

This switch Mb, MV, coil 54, 56 and relay 5
5 constitute the switching device 60.

By the way, if a resistance device is provided on the short-circuit side of the switch M6, it becomes possible to control dynamic braking and obtain a wider braking range.

Next, the braking of this embodiment will be explained. When the connection shown in FIG. 9 is for forward rotation, the signal output means 39 to the relay 5
When a signal is output on 2.53.55 to switch the switches M4 to M, one of the stator windings is set in the opposite phase by the switch M4, and Y-connected by the switch M. Also switch M6,
By switching M7, the other stator winding has its power supply terminal short-circuited while remaining Δ-connected, so an electromotive force is generated by rotation of the rotor. This generated electromotive force is absorbed by the conductor resistance of the shorted stator winding and other factors. The braking torque at this time is shown in FIG. As shown in this figure, the braking torque changes due to the rotation of the rotating stator as in the first embodiment, and as described above, by providing a resistance device on the short-circuit side of the switch M6 of this embodiment, A wide range of braking torque characteristics can be obtained.

As described above, the braking according to the present invention allows the braking torque uniquely determined by the braking device/method to be varied in various ways according to load fluctuations or changes in the load.
It has become possible to use it as a braking device for any load.

〔Effect of the invention〕

With the above configuration, the positive acceleration of the variable speed induction motor can be controlled by comparing the acceleration caused by the rotational speed of the motor or a change in the rotational speed with the process in the operation process storage unit, and also the negative (braking) acceleration can be controlled. Since the speed and speed can be controlled, there is no need for pole number switching, inverters, or mechanical transmission devices.For example, when moving loads in automated warehouses, the negative acceleration and speed that will not cause the load to collapse can be stored in the operation process memory to ensure safety. The operation of automated warehouses, etc. can be realized quickly and by the cheapest method of rotating a rotating stator.

Therefore, the use of variable speed induction motors that can generate high torque from low speeds to the rated rotation range by diversifying torque will expand, and it will be able to make even greater contributions to all fields that require high torque motors. Ta.

[Brief explanation of drawings]

Fig. 1 is a side sectional view of a multi-stator induction motor, Fig. 2 is a diagram showing the configuration of the embodiment, Fig. 3 is a block diagram of the embodiment, Fig. 4 is an operation process diagram of the embodiment, and Fig. 5 is a torque characteristic diagram of the induction motor according to the present invention, FIG. 6 is a connection diagram of the stator winding, the reverse phase device and the Y-1Δ switching device, and FIG. 7 is a simple diagram of the connection between the reverse phase device and the Y-1Δ switching device. Fig. 8 is a braking torque characteristic diagram for parallel Y connection, Fig. 9 is a connection diagram of the second embodiment, Fig. 10 is a sequence circuit diagram of the second embodiment,
FIG. 11 is a braking torque characteristic diagram of the second embodiment. 1... Variable speed induction motor, 2, 3... Rotor core,
4... Rotor shaft, 5... Non-magnetic core, 6... Rotor conductor, 7... Rotor, 8... Short circuit ring, 9...
Resistance material, 10.11... Stator winding, 12... First
Stator, 13...Second stator, l4...Machine frame, 15
... Bearing, 16... Rotating stator, 17... Gear, 2o... Rotating electric motor, 21... Drive gear, 2
2... Speed detector, 30... Power supply, 31... Electric I
Ii4 opening/closing device, 32...control unit, 33...operation process storage unit, 34...control device, 35...stator rotation device, 37...calculating means, 38...comparing means , 39
... Signal output means, 4o... Signal input means, 41.
...Control means, 42...External signal, 43...Negative phase device, 44...Y-Δ switching device, 45, 47, 50.5
1.54.56...Coil, 46.48.52.53
．． 55...Relay, 6o switching device, M, . M2. M
i. M4, MS. M6, M7...Switches.

Claims (4)

[Claims] (1) A rotor in which a plurality of conductors attached to a plurality of rotor cores provided at arbitrary intervals on the same rotating shaft are connected in a continuous manner, and a rotor that faces each of the rotor cores. a plurality of stators arranged around the rotor and having windings connected in series, and at least one stator among the plurality of stators is a rotating stator that rotates concentrically with the rotor. A variable speed induction motor according to the present invention, wherein the plurality of stators is provided with a reverse phase device for switching the direction of the rotating magnetic field of the stators in the opposite direction. (2) The variable speed induction motor according to claim (1),
A variable speed induction motor characterized in that a Y-Δ switching device is provided together with a reverse phase device. (3) The variable speed induction motor according to claim (1) or (2), characterized in that a plurality of stators are provided with voltage regulators. (4) A rotor in which a plurality of conductors attached to a plurality of rotor cores provided at arbitrary intervals on the same rotating shaft are connected in a continuous manner, and a rotor that faces each of the rotor cores, respectively. a plurality of stators arranged around the rotor and having windings connected in parallel, and at least one stator among the plurality of stators is a rotating stator that rotates concentrically with the rotor. In the formed variable speed induction motor, one stator is connected to the winding,
Features include a switching device that connects to the power supply during operation and short-circuits the winding terminals during braking, and a reverse phase device that connects the other stator winding to normal phase during operation and to reverse phase during braking. Variable speed induction motor.